(57) A method of manufacturing by a powder metallurgy process a rotary drill bit including
a bit body having a plurality of cutting elements mounted on the outer surface thereof
comprises the steps of forming a hollow mould (18) for moulding at least a portion
of the bid body, packing the mould with powdered matrix material, and infiltrating
the material with a metal alloy in a furnace to form a matrix. Before packing the
mould with powdered matrix material, there are positioned in spaced locations on the
interior surface of the mould a plurality of cutting elements, each of which is formed
of a material, such as a polycrystalline diamond material, which is thermally stable
at the temperature necessary to form the matrix. Also positioned in the mould, adjacent
the rearward side of each cutting element, is a support material (22) such that, at
least after formation of the matrix, the support material has a higher modulus of
elasticity than the matrix.
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